GMC 1976 ZEO 6083 Maintenance Manual page 231

5- 1 2
BRAKES
EXCESSIVE PEDAL EFFORT
Cause
Malfunctioning power brake.
Partial system failure.
Excessively worn shoe and lining .
Piston in caliper stuck or
sluggish .
Fading brakes due to incorrect
lining .
EXCESSIVE PEDAL TRAVEL
Cause
Partial brake system failure.
Insufficient fluid in master
cylinder .
Air trapped in system .
Rear brake not adjusting.
Bent shoe and lining.
GRABBING OR UNEVEN BRAKING
ACTION
Cause
All conditions listed under
"PULLS ."
Malfunction of combination valve.
Malfunction of power brake unit .
DRAGGING BRAKES
Cause
Master cylinder pistons not
returning correctly.
Correction
Check power brake and repair if necessary.
Check front and rear brake system and repair, if
necessary. Also check brake warning light, if a
failed system is found and light did not function,
repair as necessary.
Check and replace in axle sets .
Remove caliper and rebuild or replace.
Remove and replace with original equipment lining .
Correction
Check both front and rear system for a failure and
repair . Also, check warning light. It should have
indicated a failure.
Fill reservoirs with approved brake fluid.
for leaks. Check warning light.
Bleed system .
Adjust rear brakes and repair adjusters .
Replace axle set of shoe and lining .
Correction
All corrections listed under "PULLS ."
Replace and bleed system .
Check operation and repair, if necessary.
Correction
(NOTE : A very light drag is present
in
all disc brakes immediately after pedal
is released .)
Restricted brake tubes or hoses.
Incorrect parking brake adjust-
ment on rear brakes .
Check
With reservoir cover off, check for fluid spurt at
bypass holes as pedal is depressed. Check power
cylinder push rod, if necessary, or rebuild master
cylinder .
Check for soft hoses or damaged tubes and replace
with new hoses and new double-walled steel brake
tubing .
Check and readjust to correct specifications .